Single phase rectifier

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Single Phase Rectifier

  • Rectifier means it is convert AC voltage to DC voltage.
  • Mainly two type of Single Phase Rectifier.
  1. Single Phase half wave controlled Rectifier.
  2. Single Phase full wave controlled Rectifier.

 

Single Phase half wave controlled Rectifier.

  • Circuit description :-

    single phase half wave controlled rectifier
    fig : single phase half wave controlled rectifier
  • Fig shows the circuit diagram of half wave controlled rectifier with resistive load.
  • Circuit is energized by line voltage and secondary voltage of transformer. different  current and voltage waveform of circuit diagram are shown in fig.

    Working 

  • During positive(+ve) half cycle of supply voltage. SCR anode is positive with respect to its cathode. SCR is triggered by its properly gate pulse circuit.when SCR fired at angle α, the full supply voltage is appear across to the load.hence load is directly connected to the supply voltage.load is purely resistive load .
  • Current is flowing until SCR is commutated by reversal of supply voltage.
  • By varying the value of firing angle α we can controlled output voltage.
  • During negative(-ve) half cycle of supply voltage,
  • SCR block the flow of current.
  • No voltage appear across to the load resistive(R), hence during negative half cycle load voltage is zero.

Output wave form:

Untitled half

 Single Phase full wave controlled Rectifier

  • Two types of Single Phase full wave controlled Rectifier
  1. Mid point converter
  2. Bridge Converter

Mid point converter

  • Single phase full wave controlled rectifier circuit with mid point configuration of  Two SCRs and single phase transformer with center tap secondary winding is used.
  • Resistive load(R) is connect between center tapping and point A.
  • Mid point converter circuit Shown in fig:
Single Phase full wave controlled Rectifier with mid point tapping
fig: Single Phase full wave controlled Rectifier

Working:

  • During positive half cycle SCR S1 is ON with respect to SCR S2.
  • SCR S1 is trigger with α degree.
  • S1 is forward bias so conducting path is Vs-S1-A-R-Vs.
  • S2 is reverse bias So no current flowing through SCR S2.
  • So output voltage is getting during positive half cycle is (0+α to π).
  • During Negative half cycle SCR S2 is ON with respect to SCR S1.
  • SCR S2 is trigger with α degree.
  • S2 is forward bias so conducting path is Vs-S2-A-R-Vs.
  • S1 is reverse bias So no current flowing through SCR S1.
  • So output voltage is getting during negative half cycle is (α+π to 2π).

Output wave form:

Mid point converter
fig: Mid point converter

Bridge Converter

  • Single phase full wave controlled rectifier circuit in bridge configuration four SCRs are used.
  • Resistive load(R) is connect is shown in fig:
Bridge Converter
Fig: Bridge Converter

Working:

  • During positive half cycle S1 and S2 are forward bias and S3 and S4 are reverse bias.
  • When S1 and S2 is ON the S3 and S4 are OFF due to natural commutation.
  • During this cycle current flowing through path is Vs – S1 – R – S2 – Vs.
  • During positive half cycle S3 and S4 are forward bias and S1 and S2 are reverse bias.
  • When S3 and S4 is ON the S1 and S2 are OFF due to natural commutation.
  • During this cycle current flowing through path is Vs – S3 – R – S4 – Vs.
  • When supply voltage is zero,current become zero,hence the scr S1and S2 in positive half cycle and SCR S3 and S4 in negative half cycle turn off by natural commutation.

Output wave form:

full wave bridge rectifier
fig: waveform of full wave bridge rectifier

if any query about this single phase rectifier

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